1. Field of the Invention
The subject of the present invention is an electromagnetic device for the automated actuation of the needles of a Jacquard machine, and a Jacquard machine equipped with such a device. The invention relates more specifically to a device intended to be moved with respect to the needles of a Jacquard machine in order to push them selectively, in a selection that is established automatically on each cycle of the Jacquard machine, under the control of electromagnetic means. The invention finds a particular, but not exclusive, application in replacing the punched cards used in Jacquard machines for controlling lace-making machines, especially Leavers lace machines.
2. Description of the Related Art
It has already been proposed, particularly in European Patent Application EP-A-0 382 998, that the conventional punched cards of a Jacquard machine be replaced by an electromagnetic control device which selectively pushes the needles of the Jacquard machine. This document teaches the automatic control of the selection of each needle of the Jacquard machine using a solenoid, and more particularly a two-position solenoid comprising two concentric windings known respectively as the attraction and release windings. Electric operation of the release winding allows a selector member, in the form of a rod, to be deployed, while electric operation of the attraction winding allows this selector rod to be retracted. The device is also equipped with means allowing it to be moved with respect to the needles of the Jacquard machine. In a first embodiment, illustrated in particular in FIG. 1 of this document, the selector rod of each solenoid is associated with a passage, and its function is to close this passage when brought into the deployed position. When the device comes into contact with the needles of the Jacquard machine, all the needles which lie facing a respective passage which has been closed by a selector rod are pushed by the device when it moves. By contrast, in the case of the passages which are not closed by a selector rod, the needles of the Jacquard machine lying opposite these free passages enter the said passages when the device moves, and are therefore not pushed by this device. In a second embodiment illustrated in FIG. 4 of this document, the selector rods act respectively on intermediate pushers, and have the function of locking them in the deployed position. When a pusher is locked in the deployed position, it allows the corresponding needle of the Jacquard machine to be pushed when the device is moved. When a pusher is not locked in the deployed position, it is pushed back elastically by a return spring to a retracted position, and cannot come into contact with the associated needle.
The electromagnetic devices described in European Patent Application EP-A-0 382 998 advantageously, on the one hand, allow those needles of a Jacquard machine, which are to be pushed during a given cycle, to be selected automatically by an appropriate control of the electrical power supply to the windings of each solenoid associated with a needle and, on the other hand, allow the energy requirement for operating each solenoid to be very low. The solenoids described in this document do, however, have the drawback of being bulky and are therefore ill-suited to selecting needles in a Jacquard machine, which needles are arranged in consecutive rows with a small inter-row spacing, particularly a spacing of less than 1 centimeter.